II. The Role of Vitamins, Minerals, and Water for Proper Body Physiology

ch10_lecture_physical_activity.pdf

Home >Business & Finance homework help >Management homework help >II. The Role of Vitamins, Minerals, and Water for Proper Body Physiology

Chapter 10: Nutrition, Fitness and Physical Activity

Student learning outcomes: At the end of this chapter, you should be able to:

Describe the benefits and risks of exercise

Plan an exercise program for fitness, disease prevention, weight maintenance, or weight loss

Plan dietary intake to support exercise

Discuss pros and cons of supplements to improve performance

THINK about this – then share within a PAIR – then SHARE with the class

What does it mean to be fit?

What are the benefits of exercise?

Which types of exercise are the best?

Fitness

Set of attributes related to the ability to perform routine physical activities without undue fatigue

Defined by: endurance, strength, flexibility, body composition

Overload principle: adaptations in the body so that the body can do more

Cardiorespiratory endurance

Aerobic exercise

Lowers resting heart rate: heart pumps blood more efficiently, so it can pump less often

Increases aerobic capacity (VO2 max): muscles’ ability to use oxygen to make ATP

Increases cardiorespiratory endurance: efficiency with which the body delivers oxygen and nutrients needed for muscular activity and transports waste products from cells

Muscle-strengthening exercise

Muscle strength: enhances the ability to perform tasks such as pushing or lifting

Muscle endurance: enhances the ability to continue repetitive muscle activity

Fitness Determines range of motion, improves performance in certain activities and may reduce risk of injuries

Body composition A physically fit person has a greater proportion of muscle and a smaller proportion of fat than an unfit person of the same weight

For young adult women, desirable body fat is 21– 32% of total weight

In adult men, desirable amount is 8–19%

Health benefits of exercise

Benefits of exercise

Releases chemical endorphins: may enhance mood and aid in relaxation, pain tolerance, and appetite control

Improves mood, self-esteem, vigor, overall well-being, quality of life

Reduces depression and anxiety

Exercise & weight management

Exercise increases total energy expenditure through increased:

energy output during exercise

energy expenditure that persists for a period after exercise

lean muscle mass: increases basal needs over the long term

Exercise & weight management

Concept check

What distinguishes a fit person from an unfit one?

Why do your muscles get bigger when you lift weights?

How does exercise affect heart health?

How does exercise help with weight management?

Exercise recommendations 2010 Dietary Guidelines: > 150 minutes of moderate- intensity or 75 minutes of vigorous-intensity aerobic physical activity each week or an equivalent combination of both

Moderate-intensity exercise = walking 3 miles/hour or bicycling 8 miles/hour

Vigorous-intensity exercise = jogging > 5 miles/hour or bicycling >10 miles/hour

Muscle-strengthening activities > 2 days/week

Exercise recommendations

Aerobic zone

Aerobic activity: raises heart rate to 60–85% of maximum heart rate

Aerobic zone: exercise at an intensity in this range

Aerobic zone

Creating an active lifestyle

How can you incorporate exercise in YOUR life to meet recommendations and goals?

Creating an active lifestyle

Over Training Syndrome

Excessive training without sufficient rest to allow for recovery

Symptoms: fatigue that limits workouts and felt even at rest, decreased appetite, weight loss, muscle soreness, increased frequency of viral illnesses, increased incidence of injuries, mood changes, depression, altered sleep patterns, loss of competitive desire and enthusiasm

Concept check

How much aerobic exercise is recommended to reduce the risk of chronic disease?

What is your aerobic zone?

What types of exercise should be part of a fitness program?

Who is at risk for overtraining syndrome?

Anaerobic vs. aerobic metabolism

ATP production Anerobic metabolism: without oxygen

Only uses glucose // generates lactic acid

Aerobic metabolism: with oxygen

Uses carbohydrates, protein, and fat

More efficient; produces more ATP per glucose

Occurs in mitochondria (the powerhouse of the cell)

Oxygen delivery

Exercise duration & fuel use

First few seconds of exercise: Stored ATP is used then Creatine phosphate is broken down to make ATP

After about 15 seconds of exercise: Anaerobic metabolism uses glucose to make ATP

After 2–3 minutes of exercise: Breathing and heart rate have increased Aerobic metabolism uses glucose to make ATP

Exercise duration & fuel use

What a scientist sees

Exercise intensity & fuel use

With low-intensity activity /// ATP produced from glucose and fatty acids by aerobic metabolism

With intense exercise:

More ATP is needed

Oxygen delivery to and use by muscles limited

Muscles make ATP by anaerobic metabolism

Exercise intensity & fuel use

Fatigue

Inability to continue activity at optimal level

Occurs when glycogen stores are depleted

Occurs much more quickly with high-intensity exercise because it relies more on anaerobic metabolism, which only uses glucose

Fatigue: hitting the wall

Fitness training & fuel use

Lactic Acid Produced during anaerobic metabolism

During low-intensity exercise:

Small amounts produced are carried away from muscles and used by other tissues as an energy source or converted back into glucose by the liver

During high-intensity exercise:

Builds up in muscle then blood since amount produced > amount used by other tissues

Not a major factor in muscle fatigue

Concept check

What fuels are used in anaerobic metabolism?

What type of metabolism does a marathon runner rely on?

Why is a trained athlete able to perform at a higher intensity for a longer time than an untrained person?

Diet needs for physical activity

Energy to fuel activity // Amount of energy expended for any activity depends on the intensity, duration, and frequency of the activity and the weight of the exerciser

Protein to maintain muscle mass

Micronutrients to permit use of energy- yielding nutrients

Water to transport nutrients and cool the body

Energy expenditure during exercise

Gaining or losing weight

Healthy weight gain:

Combination of increased energy intake, adequate protein intake, and muscle- strengthening exercise to promote an increase in lean tissue vs. fat

Healthy weight loss:

Reduce energy intake by 200 to 500 Calories/day, increase activity, and change the behaviors that led to weight gain

Female athletic triad

Making weight

Macronutrient needs for physically-active individuals

Carbohydrates: 6–10 g of carbohydrate / kg of body wt/day

Fat: 20-35% of calories // Same as needs for the general population

Protein: 15–20% of calories

To maintain and repair lean tissues (e.g., muscle)

Endurance athletes: 1.2–1.4 g of protein/kilogram of body weight/day

Strength training: 1.2–1.7 g/kg/day

Macronutrient needs

Vitamin & mineral needs for physically-active individuals

Same as needs for the general population

Needed for energy production, oxygen delivery, protection against oxidative damage, and repair and maintenance of body structures

Increased use and loss with exercise

DRIs acknowledge that the iron requirement may be 30 to 70% higher for athletes than for the general population

Sports anemia

Water needs for physically-active individuals

Exercise increases water needs because it increases losses in sweat and respiratory system evaporation

Risk of dehydration is greater in hot than cold environments but can occur in the cold

Water is needed to cool the body and transport oxygen and nutrients to the muscles and remove waste products from them

Dehydration & performance

If a person loses 4% of their body weight as water during a competition, by what percentage will their performance be decreased by the end of the event?

a) It will not be affected b) 10% c) 20% d) 25% e) 30%

Dehydration

Occurs when water water loss is great enough for blood volume to decrease

Reduces the ability of the circulatory system to deliver oxygen and nutrients to muscles

Reduces blood flow to the skin and sweat production limiting the body’s ability to cool itself

Can increase core body temperature and heat-related illnesses

Heat-related illnesses Heat cramps: involuntary muscle spasms during or after intense exercise

Heat exhaustion: Decreased blood volume, ability to cool the body and oxygen delivery

Rapid but weak pulse, low blood pressure, disorientation, profuse sweating, fainting

Heat stroke: core body temperature rises above 105°F causing decreased sweating

Hot, dry skin; extreme confusion; unconsciousness

Heat index

Hyponatremia Decreased blood sodium

Early symptoms: nausea, muscle cramps, disorientation, slurred speech, confusion

Can cause water to move from blood to tissues by osmosis causing swelling

In the lungs: interferes with gas exchange

In the brain: causes disorientation, seizure, coma, death

Sweating results in loss of sodium

During endurance events, sweat needs to be replaced with water AND sodium

Hyponatremia

Fluid recommendations for exercise

Generous amounts of fluid in the 24 hours before an exercise session

About 2 cups of fluid 4 hours before exercise

6–12 ounces of fluid every 15–20 minutes for the duration of the exercise

After exercise, each pound of weight lost should be replaced with 16–24 oz (2 to 3 cups)

Fluid recommendations for exercise

For exercise lasting an hour or less, water is the only fluid needed

For exercise lasting more than an hour, beverages containing carbohydrate (about 10 to 20 g of carbohydrate/cup) and electrolytes (around 150 milligrams of sodium in a cup) are recommended

Fruit juices and soft drinks are not recommended unless diluted with an equal volume of water

Dietary carbohydrate & endurance

Glycogen super-compensation

To substantially increase muscle glycogen stores before competition

Rest for 1–3 days before competition while consuming a very high-carbohydrate diet

10–12 g carbohydrate/kilogram of body weight/day

Beneficial to endurance athletes

Disadvantages if exercising < 90 minutes

What to eat before exercise

Enough fluid to maintain hydration High in carbohydrate (60 to 70% of calories) Contain about 300 Calories Moderate in protein (10 to 20%) Low in fat (10 to 25%) Low in fiber Avoid spicy foods Avoid large amounts of simple sugars

What to eat before exercise

What to eat during exercise lasting more than an hour

Consume carbohydrate

Particularly important for exercise in the morning, when liver glycogen levels are low

Carbohydrate intake should begin shortly after exercise begins

Regular amounts should be consumed every 15–20

minutes during exercise, about 30–60 grams/hour

Should provide glucose and fructose

Consume sodium

What to eat after exercise

Replace lost fluids

Replace glycogen stores:

For 30–60 minutes of daily exercise, a typical diet with about 55% of calories is sufficient

For serious athletes competing on consecutive days, a high-carbohydrate meal or drink (1–1.5 g of easily absorbed carbohydrate per kilogram of body weight) should be consumed within 30 minutes and every 2 hours for about 6 hours

Concept check Why might a low-carbohydrate diet be a poor choice for an endurance athlete?

Why is dehydration more likely when it is hot and humid?

How much of what fluid should you drink during a two-hour bike ride?

What should a athlete eat as a precompetition meal and why?

Ergogenic aids Substances, appliances, or procedures that improve athletic performance

Many vitamins, minerals, and substances in these supplements help provide energy for exercise or promote exercise recovery

Most do not improve athletic performance; a few have a small effect compared a healthy diet

Most are promoted based on their function, but supplementation does not improve function

Diet, supplements & performance

Growth hormone (GH)

Increases muscle protein synthesis but has not been shown to enhance muscle strength, power, or aerobic exercise capacity

Improves anaerobic exercise capacity

Can cause heart dysfunction, high blood pressure, excessive growth of some body parts

Ornithine, arginine, and lysine stimulate GH release but do not cause muscle mass/strength increases more than exercise alone

Anabolic steroids

Synthetic fat-soluble hormones that mimic testosterone

Accelerate protein synthesis

Increase muscle size and strength

Steroid precursors (e.g., androstenedione, or andro) can be converted into steroids in the body but have not been found to increase testosterone levels or have ergogenic effects

Anabolic steroids – side effects

Decrease testosterone secretion leading to testicle shrinkage and decreased sperm production

Stunted height in adolescents

Oily skin, acne, water retention in the tissues, yellowing of the eyes and skin, coronary artery disease, liver disease, death, psychological and behavioral changes (violent outbursts, depression, suicide)

Anabolic steroids – side effects

Ergogenic aids in short, intense activities

β-hydroxy-β-methylbutyrate (HMB): studies found a small increase in strength in previously untrained men; trivial effects in trained lifters

Bicarbonate: acts as a buffer to neutralize acid to delay fatigue and improve performance

Causes abdominal cramps and diarrhea

Creatine: used to make creatine phosphate to provide quick energy for short-term maximal exercise; may increase muscle mass/strength

Creatine

Ergogenic aids in endurance activities Increase fat or oxygen available to muscle cells

Carnitine: fat burner - increases fat utilization during exercise to spare glycogen; supplements have not been shown to increase endurance

Medium-chain triglycerides (MCT): cause blood fatty acids levels to rise increasing availability of fat as a fuel; supplements have not been shown to increase endurance, spare glycogen, or enhance performance

Ergogenic aids in endurance activities Caffeine: enhances fatty acids release to use as a fuel source so less glycogen is used and fatigue onset is delayed

Improves concentration, enhances alertness

May impair performance by causing GI upset

3–6 mg of caffeine per kilogram of body weight (about 2.5 cups of coffee) up to an hour before exercising and smaller doses during exercise (1 to 2 mg/kg) improve endurance

Debate Are Energy Drinks a Good Way to Enhance Athletic Performance?

Erythropoitin (EPO)

Produced by the kidneys to stimulate red blood cell production

Can enhance endurance by increasing the ability to transport oxygen to the muscles to increase aerobic capacity and spare glycogen

Too much can stimulate too many red blood cells leading to blood clotting, heart attacks, strokes, death

Concept check

How do anabolic hormones affect the production of testosterone?

Why are creatine supplements beneficial for sprint and strength athletes?

How does caffeine increase endurance?

Applications

What advice could you give about food, water, and supplement consumption to a friend who is an athlete?

Nutrition in the news

Energy drinks Energy drinks + alcohol Making weight Eating disorders in athletes Steroids in baseball and other sports Banned substances in cycling, track and field, and other sports

Checking student learning outcomes

What are the benefits and risks of exercise?

Which types of exercise programs could you follow for fitness, disease prevention, weight maintenance, or weight loss?

What advice would you give to a loved one about dietary intake to support exercise?

What are the pros and cons of supplements to improve performance?